There’s something about open space in Seattle that prize juries seem to love. Weiss/Manfredi’s Olympic Sculpture Park, for instance, won the prestigious Veronica Rudge Green Prize in Urban Design in March—and, just last month, it received an American Society of Landscape Architects (ASLA) general design honor award. ASLA also gave an honor award to Open Space Seattle 2100, a plan for building green spaces throughout the city during the next 100 years.

With the Olympic Sculpture Park, Weiss/Manfredi worked with landscape architect Charles Anderson to transform a nine-acre industrial brownfield in central Seattle into a venue for the Seattle Art Museum’s sculpture collection. Composed of a series of grassy, angular terraces, the space also serves as a green space that connects and crosses Seattle’s urban fabric, helping restore the relationship of the city to the Puget Sound.

Harvard University’s Graduate School of Design sponsors the biennial Green Prize, which recognizes excellence in urban design with an emphasis on projects that contribute to the public realm of a city. Weiss/Manfredi’s selection marks the first time a winning project has been located in the U.S. during the prize’s 18-year history.

Open Space Seattle, meanwhile, is the product of a grassroots advocacy campaign that involved design professionals as well as the Department of Landscape Architecture at the University of Washington. The group conceived plans for what it called “green infrastructure”: a network of parks, civic spaces, shorelines, and forests that link Seattle’s neighborhoods to one another and provide open spaces for all its citizens.

Weiss/Manfredi will receive the Green Prize at a December 5 ceremony in Cambridge, Massachusetts. ASLA, meanwhile, presents its awards at the organization’s annual meeting on October 8 in San Francisco.